• Embryology: 6^th week – indifferent gonads (cortex, medulla)
• 7^th-8^th week – medulla Þ testis, cortex Þ regresses.
• testes descend from abdomen through inguinal ring; reach scrotum by birth
• Histology: tubular gland, tunica albuginea (dense fibrous capsule), tunica vascularis (blood vessels in connective tissue), tunica vaginalis (peritoneum, anterior and lateral surfaces)

• approx. 250 lobules, each containing
• 1-4 seminiferous tubules in loose CT (blood vessels, lymphatics, nerves)
• Function: produce spermatazoa (sperm) and testicular fluid
• seminiferous Þ tubuli recti (straight tubules) Þ rete testis Þ ductuli efferentes (12-15) Þ Cauda epididymidis Þ ductus deferens Þ ejaculatory duct Þ urethra
• maintenance of stucture is dependent on FSH and LH
• 2 types of cells:
• (1) Supporting cells (Sertoli cells)–extend from basement membrane to lumen around spermatogenic cells, tight junctions between cells
• provide nutrient and support for sermatocytes, spermatids, and spermatozoa; responsible for release of sperm and production of fluid; phagocytosis; androgen binding protein (ABP) production (maintains testosterone, FSH Ý synthesis of ABP)
• (2) Reproductive cells – spermatagonia (basal lamina) Þ spermatocyte Þ spermatid (lumen of tubule)
• Spermatogenesis: germ cells (spermatagonia) proliferate into mature spermatids
• (1) Spermatocytogenesis – spermatagonia give rise to spermatocytes
• (2) Meiosis–46 chromosomes (diploid) undergo 2 divisions resulting in 4 spermatids (haploid, 23 chromosomes each)
• (3) Spermiogenesis – differentiation to spermatozoon (Golgi, cap, acrosome, and maturation phases)
• Interstitial cells (Leydig Cells) – distributed in the stroma between the seminiferous tubules
• Function: produce testosterone - attainment and maintenance of accessory glands (seminal vesicles, prostate, bulbourethral glands), sperm production, development and maintenance of secondary sex characterisics
• Histology: large ovoid nucleus, vacuolated cytoplasm (lipid granules, droplets), well-vascularized
• Embryology: from mesenchyme (not epithelial cells)
• Regulation: LH stimulates testosterone production

• Straight tubules (tubuli recti) – joins the seminiferous tubules with the rete testis
• Histology: tall columnar epithelium, Sertoli-like cells, no germ cells (no spermatogenesis)
• Rete testis – sinusoidal area that connects the straight tubules with ductuli efferentes in the mediastinum testis
• Ductuli efferentes–12 or more efferent ductules on posterior testis; coil to form caput epididymidis (head of epidid.)
• Histology: pseudostratified epithelium; ciliated; facilitate transport of sperm – also non-ciliated absorptive cells; surrounded by circular smooth muscle
• Overall Function – remove excess fluid and extraneous materials carried with spermatozoa, nutrients for spermatozoa are added in this area
• Epididymis – has head, body, and tail
• Histology: tall pseudostratified columnar epithelium (Proximal convoluted part)
• small basal cells – near basement membrane
• columnar cells – covered with non-motile stereocilia
• Function: participates in absorption and digestion of cytoplasmic fragments eliminated during spermatogenesis; spermatozoa become motile and fertile
• Vas deferens (ductuli deferens) – tubular structure which leaves the epididymis
• Histology: epithelium overlying a lamina propria (Ý elastic fiber content). Along the length of the epididymis the epithelium loses its sterocilia and becomes pseudostratified
• 3 muscular layers: inner longitudinal, middle circular (thickest), and outer longidtudinal.
• adventitia – loose connective tissue with elastic fibers.
• cremaster muscle, vascular and neural supply, veins (pampiniform plexus) included in spermatic cord
• Ampulla – dilation of the ductus deferens after crossing the ureter in the abdominal cavity
• Seminal vesicle – large glandular evagination (outpocketing of the wall of the ampulla)
• Histology: epithelium – tall columnar cells
• lamina propria – 2 layers of smooth muscle (inner circular, outer longitudinal); thick CT with elastic fibers
• Regulation: level of testosterone (varies with age)
• Function: thick sticky secretion containing fructose, flavins, prostalglandins (provides nutrient to spermatazoa)
• Ejaculatory duct – connect ampulla to the urethra through the prostate gland
• Histology: simple or pseudostratified columnar epithelium (secretory in function), no muscular coats
• Prostate gland – 30-50 small, compound tubulo-alveolar glands embedded in a mixture of smooth muscle and fibrous connective tissue. Surrounded by a thin capsule (connective tissue, smooth muscle fibers)
• 3 types of glands in prostate:
• (1) Periurethral glands (mucosal) – smallest, around urethra
• benign prostatic hypertrophy or hyperplasia (BPH) –glands commonly overgrow to form nodules
• (2) Submucosal glands – surround the periurethral tissue
• (3) Main Prostatic Glands (external, proper)–outer largest portion of gland; provide most prostatic secretions
• Histology: greatly folded epithelial lining (accomadate stored secretion), epithelium (tall columnar cells) resting on a lamina propria (fibrous connective tissue, abundant capillary supply)
• Function: produce and store secretion (thin, milky fluid with acidic pH in citric acid)
• contains acid phosphatase, dependent on androgen
• Urethra – long tube where the ejaculatory ducts and prostate glands empty, opens at the end of the penis. 3 parts:
• (1) Pars prostatica – surrounded by prostate gland
• (2) Pars membranacea – extends from base of prostate to base of penis
• (3) Pars spongiosa – passes lengthwise through the penis
• Bulbourethral glands – pair of compound tubuloalveolar glands at the base of the penis.
• Function: coat lining of urethra with clear, viscid, mucus-like lubricant (suitable environment for spermatozoa)

Penis – conductance of sperm into vagina

• Anatomy: 3 cylindrical masses of erectile tissue (left and right corpora cavernosa and corpus spongiosum)
• corpora cavernosa penis – lie side by side, superior to the corpus spongiosum
• corpus spongiosum (corpus cavernosum urethrae)–transmits urethra; distal end forms glans penis, surrounded by tunica albuginea
• Arterial supply: terminal branches of the internal pudendal arteries
• 2 dorsal arteries on dorsal surface of tunica albuginea
• cavernous artery running longitudinally in each corpus cavernosum
• 2 bulbourethral arteries that enter corpus cavernosum urethrae.
• Venous drainage: superficial dorsal v. (drains glans and corpus spongiosum), deep dorsal vein (drains corpora cavernosa)
• in erectile tissue, there is a network of large, thin-walled veins spearated by trabeculae of connective tissue
• Erection: conversion of penis from flaccid to rigid organ
• caused by dramatic Ý in vascular pressure within erectile tissue from erotic stimuli evoking parasympathetic activity
• Mechanism: Parasympathetic activity has two effects:
• (1) Closes arteriovenous shunts – Ý arterial pressure to flow entering tunica albuginea
• (2) Dilates helicine arteries – act as arteriovenous shunts in erectile tissue
• these lead to inflation of the corpora cavernosa to the limits of the tunica albuginea
• Flaccidity (detumescence) – reversal of changes in arterial supply Þ ß pressure in erectile veins
• Ejaculation: reflex phenomenon that involves parasympathetic and sympathetic innervation
• afferent impulse: sensory impulses from the penis transmitted by internal pudendal neves to spinal cord
• efferent impulse: integrated sensory information returned to smooth muscle of genitals via para and symp routes
• sympathetic – leave upper lumbar segments through lumbar rami communicantes, hypogastric nerves through hypogastric plexus Þ evokes movement of semen into the urethra
• parasympathetic – via the internal pudendal nerves Þ provoke ejaculation
• Semen: product of ejaculation; ejaculate (3.5 mL) contains motile sperm and secretions of ducts and accessory glands
• Sperm density – 500,000 to 1.5 million per ml. Sperm can live a few days in the uterus and fallopian tubes
• Orgasm: sensation associated with ejaculation
• origin, mechanism, and location of sensations not fully known